Alternator Problem?

Hi

I had a problem with my MG TF 02 135 not charging when driving up to the Lakes this weekend. The battery went flat as I was driving.
I was stranded so bought a new battery and alternator. With a bit of help from the lovely team at Kwik Fit Kendal, I had the alternator changed and the car back up and running with a voltage of 14.5v when started. I drove home on Sunday. It was very wet, with wipers, headlights and heater fan on for an hour and a half. Lights were dimming after about an hour but no charging light on the dash. Checked the battery and 10.6v across the terminals when the engine was running and when switched off. Checked the alternator fuse. That was OK just cleaned the terminals. The alternator is running with the belt OK, positive feed and D electrical plug fitted. Put the battery on charge for a while. I then got 11.8v across battery terminals when engine running and off. Checked the positive feed at the alternator to earth on the chassis and on the case of the alternator, still 11.8v when engine running or not. So nothing coming out of the alternator. Disconnected the positive feed to the alternator and started the car, there is 0.5v at the alternator output to the alternator frame or car chassis?
What do you think is the new alternator faulty? Any suggestions?

Hi and welcome to the forum

How are your earths?

James

Thanks James.
I haven't checked them other than a quick visual. I will replace the battery and engine earths as a matter of course.
I assumed if I had the same voltage at the alternator case as across the battery they must be OK. What do you think?
Cheers Steve

Hi . When you say you have no charging light on the dash , do you mean there was no light on with the engine running or with just the ignition on ? As you probably don't need telling , you need the ignition light to work for the alt to charge . I would suspect the alternator as I presume it was a reconditioned unit and there are varying differences in how they are ' remanufactured ' these days !
John

Hi John
The ignition warning light is not on when the engine is running but is on when the ignition is on and the engine not running.
The Alternator is Remy remanufactured.
Have tried connecting a long jump lead from the alternator case to the battery negative. The battery is 12.3v when the engine is off or on. Get the same voltage across at the alternator +ve to the alternator case.
Cheers Steve

Well it's always difficult to diagnose from a distance but I would say its the alternator .
With a fully charged battery if there is nothing showing from the alternator main lead when running , I'd say its goosed.

John .

Thanks John
I will strip it back out and put in the old one with a new regulator from eBay
Cheers Steve

I had a similar problem with my TF. Being low mileage I thought I would fit a regulator and that was 5 years ago now and it's still OK. I know I'll get a few comments about remanufactured units but I have had plenty of experience in the motor trade of poor quality items . Hope you're sorted soon .
John

Thanks. I will post an update when re-fitted. The regulator is on order.
Cheers Steve

A mechanic friend of mine repaired my neighbours car recently with an alternator fault. He already had two new alternators fitted but still had the battery draining. He told me that Eurocarparts were supplying faulty alternators and many were not charging the batteries properly - if at all!
He took the "new" alternator off and give it to a local alternator repair expert and he sorted it out. So a new alternator may not be all it should be.
Just thought I would mention this as it should not be discounted as the problem even if it has been replaced.

Sundance

The new alternator was refunded by the supplier as faulty

I fitted a new regulator to the old alternator for less than 30 quid and she has been fine since